'Sometimes we may have to modify some of our freedoms'

John Reid was due to give a major speech on immigration on Wednesday as part of his ongoing restructure of the Home Office. Instead, he devoted his address to terrorism, speaking passionately about the nature of the threat and how critics of police and government tactics were putting national security at risk.

"They just don't get it," he said. "Sometimes we may have to modify some of our own freedoms in the short term in order to prevent their misuse and abuse by those who oppose our fundamental values and would destroy all of our freedoms in the modern world," he told the Demos thinktank.

Mr Reid may not have known then that the police were going to have to act within hours of his speech, but he would have known about the details of the plot and that the police and the security service were going to act, probably within days.

He said that Britain was facing "probably the most sustained period of severe threat since the end of the second world war" and that the country was being confronted by a new breed of ruthless "unconstrained international terrorists".

Everyone across the political, media, judicial and public spectrums needed to understand the depth and magnitude of the threat, he said.

Mr Reid's targets were judges, political commentators and British politicians.

He pointed out that laws designed to deport and detain had been repeatedly weakened by liberal opposition. Drawing on recent research by Demos, he added: "If more violent attacks on UK citizens are to be stopped, the public, corporations - everyone - will have to do its part to help."